Brushless electric motors are well known in the art and are characterized by internal electric circuitry which provides for electrical commutation. Brushless direct current (D.C.) motors are routinely produced in high volume for use in a multitude of industrial applications such as fan motors. As a result, it is imperative that the design of the motor be simple and adaptable to low cost automated assembly techniques.
Known brushless direct current motors include the electric fan motor No. TA 300 D.C. manufactured by the NIDEC Corporation of Torrington, CT. This motor includes a rotor having an external impeller and a housing. Concentric with the rotor is a stator and a printed circuit board, both mounted within the housing. On the printed circuit board is an electrical component which comprises a commutating circuit. The circuit contains a sensor, typicall a Hall cell, which is used as a trigger. These sensors are characterized by a limited range and therefore must be very carefully located with respect to the stator and the rotor. The printed circuit boards used conventionally with these motors are two dimensional and lack any intrinsic means for fixturing with other motor components. Consequently, the printed circuit board must be manually affixed within the housing in a position which will ensure that the sensor is located with respect to the other motor components within a precise range. The absence of any self-fixturing mechanism within known printed circuit boards also precludes the use of automated assembly techniques with respect to the printed circuit board, and ultimately limits the adoption of automated assembly techniques with respect to the other motor components as well.
To accomplish precise sensor location, known brushless electric motors using a conventional two dimensional printed circuit board require separate positioning of the sensor out of the plane of the printed circuit board. These motors are characterized by a separate pedestal or an equivalent that must be attached to the printed circuit board. A separate pedestal offers only marginal improvement in the accuracy of the sensor location and adds another labor intensive step to the motor assembly process.
It would be advantageous to have a printed circuit board for use in a brushless electric motor which includes a mechanism for self-fixturing with other motor components and which results in simplified assembly with other motor components, and which further would provide for a precisely located sensor. The present invention is drawn toward such a printed circuit board.